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Math Help - Quadratic inequalities

  1. #1
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    Quadratic inequalities

    mathsyahoo.jpg picture by Helena-Rossouw - Photobucket

    can any1 plz help me with number 4 and 6 ooh and 5 if u feel generous..

    number 6s text isn't clear..
    it says:
    Using the graphs explain where the product of the two straight lines will be zero, positive and negative.
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  2. #2
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    For (4) you need to know that the area of a rectangle is the product of the length and width.

    For (5) and (6) the product of two positive or two negative numbers is positive while the product of one positive and one negative number is negative.
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  3. #3
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    i think 4 a) is -h^2 + 6h -5 ??

    but i still dnt get number 6
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  4. #4
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    Talking

    Quote Originally Posted by Helena-Rossouw View Post
    i think 4 a) is -h^2 + 6h -5 ??
    You are given that the dimensions of the rectangle are 5 - h and h + 1. Multiply these two expressions to find the expression for the area.

    Quote Originally Posted by Helena-Rossouw View Post
    but i still dnt get number 6
    You are given a graph of two straight lines, and asked to say "where the product of the two straight lines will be zero, positive and negative", by which I would guess they mean "the x-values for which the product of the corresponding y-values will be zero, positive, or negative".

    For a product of two values to be positive, what must be the signs on the two numbers? For a product of two values to be negative, what must be true of the two signs? For a product of two values to be zero, what must at least one of the values be?

    Use this information to figure out the intervals of sign on the graph, keeping in mind that "on the x-axis" means that y is zero, "above the x-axis" means y is positive, and "below the x-axis" means y is negative.

    Hope that helps!
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